This invention relates generally to high speed connectors that are used as vertically stacked receptacle connectors, and more particularly, to connectors utilizing insert wafers that incorporate differential signal terminals which are positioned alongside each other where they appear in the connector receptacle portions and which are turned at their tail portions for joining to a printed circuit board.
Electrical connectors are well known to those of ordinary skill in the electronic arts as generally reliable devices by which electrical signal paths can be extended into and obtained from a printed circuit board. Over the last several years, however, electronic devices and systems have gotten both smaller and faster, making reliable connectors more difficult to design, manufacture and install onto printed circuit boards.
In a connector used in high-speed applications, crosstalk that is likely to occur between closely spaced, high-speed signal paths can be reduced by using differential-voltage signals. A differential signal pair is a pair of terminals or other conductors that together carry a signal but neither of the two conductors is at ground or reference potential. Rather, the voltage on one conductor of a differential pair is, at any given instant, the same magnitude, but opposite polarity as the voltage on the other conductor. A differential pair therefore is analogous to a transmission line, the conductors of which are capacitively and inductively coupled to each other. Crosstalk between two or more differential signal pairs as well as interference of one differential pair on another can be significantly reduced if a good ground plane (or other fixed-voltage reference plane) is provided between the conductors of one differential pair and the conductors of another differential pair as a sort of shield between them.
Each differential signal pair requires at least two capacitively coupled conductors, and it is important for a connector that links a differential signal pair between devices or circuit boards to maintain capacitive coupling. When a connector is used to provide an edge connection for a circuit board or is used as a plug connector, arranging differential signal pairs in a connector so that they are alongside each other and next to each other on the same side of a circuit board can cause the connector width to increase, but when the connector is installed onto a circuit board, connector width should be minimized.